In recent years, these electronic devices made of organic materials have been actively studied. These electronic devices (organic electronic devices) can be mounted on flexible and large-area substrates and can be manufactured in a low-temperature process at low cost, for example. These advantages over conventional electronic devices made of inorganic materials are expected to realize, for example, practical flexible displays etc.
Examples of the organic electronic device includes organic electroluminescent (hereinafter referred to as “organic EL”) device, organic photovoltaic cells, and organic field-effect transistors (organic FETs), etc.
The organic EL device includes an organic EL element in which an organic layer containing a luminescent material is interposed between a pair of electrodes. The organic EL element has characteristics, such as low voltage drive, high luminance, light emission capability, etc., and therefore, can have a smaller thickness and a lower weight. The organic EL device is applicable to a light source for a photocopier and a printer, etc., and an illuminating device in addition to a display. For example, an organic EL illuminating device has a number of advantages, such as surface emission, smaller thickness, ease of dimming control, etc. While fluorescent lamps contain mercury, which puts a load on the environment, the organic EL illuminating device is free from such a problem.
As a technique of mass-producing an organic EL element at low cost, there is a known manufacturing technique of forming an electrode and an organic layer, etc. on a flexible substrate, such as resin film etc., by roll-to-roll processing (e.g., PATENT DOCUMENT 1).
In roll-to-roll processing, the substrate is conveyed intermittently or continuously during or between each production step, such as electrode formation, organic layer formation, etc., to form an electrode and an organic layer, whereby the time required for the production step can be shortened and the size of the device can be reduced.
In general, flexible substrates made of resin film etc. transmit moisture and oxygen more easily than glass substrates. Therefore, if the organic electric-field element is exposed to the atmosphere, the organic electric-field element is likely to be degraded due to moisture and oxygen, etc.
PATENT DOCUMENT 2 and NON-PATENT DOCUMENT 1 describe organic EL elements including a flexible film substrate, in which a barrier layer made of an oxide or nitride of silicon or aluminum, etc. is provided on a surface of the substrate to enhance the gas barrier properties of the substrate.
PATENT DOCUMENT 3 describes an organic EL element including a flexible film substrate, in which the organic EL element is encapsulated by a glass substrate and a moisture-resistant film to reduce or prevent external moisture which enters the organic EL element.